(1) Field of the Invention
The present invention relates generally to an automatic piano playing instrument, and more particularly to a solenoid driving apparatus for actuating keys of a player piano.
(2) Description of the Prior Art
FIG. 1 is a diagrammatic illustration of a prior art automatic piano playing instrument showing briefly a construction thereof. Such instrument is shown in the U.S. Pat. No. 4,132,141. In the figure, a reference numeral 1 denotes a key of a piano which is pivoted about a fulcrum 2 in such a way that an end portion 1b of the key is moved upward when an operating portion 1a opposite to the end portion 1b is depressed downward. The upward movement of the end portion 1b is transmitted to a piano action 3 which actuates a hammer 4 to strike a string 5.
By depressing the operating portion 1a of the key 1, a key switch 8 comprising a flexible spring 6 and a contact point 7 is turned on. Musical tones produced by the string 5 are received by a microphone 9 for the transference thereof to a record control circuit 10, one or two microphones 9 being commonly used for one piano. The record control circuit 10 detects whether each of all the keys 1 is depressed or not sequentially in response to an output from the corresponding key switch 8 thereby periodically delivering a key data which represents each key is depressed or not to such a data recorder 11 as a cassette tape recorder. Simultaneously, the record control circuit 10 detects the strength of a key striking motion in accordance with an output from the microphone 9 thereby delivering a key striking strength data representative of the strength of a key striking motion to the data recorder 11. The data recorder 11 is activated (or the magnetic tape thereof is started to move) at the start of playing the piano in order to record sequentially the aforementioned key data and key striking strength data.
The above steps are concerned with the recording of a musical performance data generated by a player. Conversely, when the recorded musical performance data is requested to be reproduced, the data recorder 11 transfers sequentially in real time the recorded data to a reproduction logical circuit 12. In the circuit 12, a key data and a key striking strength data are reproduced in accordance with the data from the data recorder 11 for the delivery to a solenoid driving circuit 13. The solenoid driving circuit 13 generates a solenoid driving signal in accordance with the key data and key striking strength data supplied thereto, the solenoid driving signal being supplied to a corresponding solenoid 14. Then, the plunger 14a of the solenoid 14 is driven upward with a speed corresponding to the key striking strength data, thereby urging the end portion 1b of the key 1 to move upward with the upper end of the plunger 14a being in contact relation to the bottom surface of the key 1 adjacent to the end portion 1b. The upward displacement of the end portion 1b is transformed via the piano action 3 into the striking motion of the hammer 4, thereby striking the string 5 with a force corresponding to the key striking strength data.
One of typical conventional automatic piano playing instruments or player pianos has been described above in brief. In such automatic piano playing instruments, however, an energy to be applied with solenoid 14 is determined by the magnitude of key striking strength data, and the key striking strength data is determined by the tone magnitude which is pick up by the microphone 9.
Therefore, paticularly when a plurality of keys are concurrently depressed, the key striking strength data for plural keys are determined at the same magnitude, and accordingly respective key striking strength data cannot correspond to respective key striking strength. Consequently, it is difficult to reproduce the musical performance data with high fidelity.
Further, each solenoid is driven in accordance with the key striking strength data, however, energy which are required at respective keys are different from each other when the respective keys are driven by the same key striking strength.
That is, according to characteristics of solenoids and actions, positions of solenoids, and the kind of keys (white keys or black keys, and higher pitch keys or lower pitch keys), energy required when the keys are driven by the same strength are different from each other.
Therefore, also due to this fact, it is difficult to reproduce the musical performance data with high fidelity.